Science of Synthesis

Wicha, J., Science of Synthesis, (2009) 48, 102.

Various ketones are deoxygenated when treated with zinc dust in acetic anhydride or in dry organic solvents, such as diethyl ether, benzene, or hexane, saturated with gaseous hydrogen chloride (‌Table 1‌).[‌17‌,‌18‌,‌42‌] The reaction occurs at a low temperature (0°C) and is relatively fast (1–2 h), which permits some selectivity. Representative saturated ketones such as cholestan-3-one (entry 1) afford the deoxygenated products in high yield, either in diethyl ether or in acetic anhydride. For the reduction of polyfunctional compounds, the reaction conditions (solvent, acid concentration, and temperature) appear to be substrate-tailored. A macrocyclic oxo lactone undergoes selective deoxygenation, with the lactone moiety remaining unaffected, on treatment with zinc in dibutyl ether saturated with dry hydrogen chloride (entry 2).[‌43‌,‌44‌] A decahydroquinoline derivative is reduced with zinc in anhydrous diethyl ether at −20 to 0°C (entry 3); partial epimerization at the stereogenic center in the position α to the carbonyl group (C5) occurs concomitantly.[‌45‌] A complex carbazole derivative affords a 4:1 mixture of the corresponding amides on reduction with amalgamated zinc in ethanol saturated with gaseous hydrogen chloride (entry 4).[‌46‌] Reduction of a ketone with zinc dust in the acetic anhydride/tetrahydrofuran/trifluoroacetic acid system has been reported.[‌47‌]

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Meeee	M8,M8	Meeeeeeeee	Meeee (%)	Mee
8		Me, MMe(e), Me8M, 8°M	88e	[‌88‌,‌88‌]
8		Me, MMe(e), Me8M, 8–88°M, 8.8 e	88	[‌88‌]
8		Me, MMe(e), Me8M, −88 ee 8°M, 8 e	88e	[‌88‌]
8		Me/Me, MMe(e), MeMM, eeeeee, 8 e	88e	[‌88‌]

e 88% eeeee eeee eeeeeee ee Me8M.

e M eeeeeee ee (8M)- eee (8M)-eeeeeee ee e 8:8 eeeee ee eeeeeeee.

e M 8:8 eeeeeee eeee eee eeeee eeeeeeeee eeee eeeeeeeee ee eee eeeee eeeeeeee eeeee ee eeeeeeee.

Meeeeeeeeeee Meeeeeeee

8α-Meeeeeeeee (‌Meeee 8‌, Meeee 8); Meeeeee Meeeeeeee:[‌88‌]

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(8M,8eM,8eM)-8-Meeeeee-8-eeeeee-8-eeeeeeeeeeeeeeeeeeeeeeee (‌Meeee 8‌, Meeee 8); Meeeeee Meeeeeeee:[‌88‌]

Me eeee (88.8 ee, 8.88 eeee) eee eeeee ee e eeeeeee eeee ee (8M,8eM,8M,8eM)-8-eeeeeee-8-eeeeeeeeeeeeeeeeeeeeeee-8-eee (88.8 ee, 8.888 eeee) ee Me8M (8.8 eM) eeeeeeeee eeee MMe(e) ee −88°M. Mee eeeeeeeeee eee eeeeeee ee eeee ee 8°M. Meeee e eeeeeee 8 e, eee eeeeeee eee eeeeee eeee eeeeeee eee. Mee eeeeeee eeeee eee eeeeeeeee eee eee eeeeeee eeeee eee eeeeeeeee eeee Me8M (88 eM). Mee eeeeeeee eeeeeee eeeeeee eee eeeeee eeee eeeee (8 eM) eee eeeee, eee eee eeeeeee eee eeeeeeeeee. Mee eeeeeee eee eeeeeeeeeeeeeee (eeeeee eee); eeeee: 88.8 ee (88%); eeeee (8M/8M) 8:8.

References

Meeeeee Meeeeeeeeee

• 8.Meeeee-Meee, (8888) M 88e8, 888.
• 8.Meeeee-Meee, (8888) M 8e, 88.